Persons with partial and total walking disabilities have traditionally relied upon wheelchairs for locomotion. Wheelchairs generally have relatively widely spaced wheels for lateral stability and to comfortably accommodate the occupant. Persons in wheelchairs can move with relative ease in places such as hospitals which are usually provided with extra wide doors and halls and inclined ramps between vertically displaced levels. However, private homes and work places are generally not planned specifically to accommodate wheelchairs. While wheelchairs are generally resistant to lateral tipping, they are often designed for tipping backwards so that an attendant pushing a patient in a wheelchair can tip the front wheels up to negotiate such obstacles as steps, threshholds, and the like. While such a configuration is useful when the wheelchair is pushed by an attendant, the design presents some hazards when the wheelchair occupant attempts to wheel himself up a ramp. Further, there is a degree of social stigma attached to wheelchairs such that wheelchair occupants are sometimes shunned as "handicapped".
In order to overcome some of the problems associated with wheelchairs, the medical equipment industry has developed small personal mobility vehicles as an alternative. Such vehicles generally have a pair of rear wheels, a steerable front wheel, are powered, and in general have the appearance of a downsized golf cart. The track of the rear wheels is generally narrower than that of wheelchairs, the wheel base is generally longer than that of wheelchairs, and the vehicles are usually designed for tight turning radii such that the vehicles are more maneuverable than wheelchairs and, therefore, more useful in places which are not specifically designed for wheelchair use.
Of the known vehicles of this type, most are front wheel driven. One of the problems with front wheel drive in such vehicles is that the weight of the occupant is usually concentrated near the rear wheels such that when there is resistance to motion of the vehicle as in ascending ramps, the driven front wheel simply spins. In the only known rear wheel drive unit, each of the rear wheels is driven by its own motor and the wheels are differentially interconnected. In addition, this particular vehicle employs a pair of batteries. The use of duplicate motors and batteries results in a vehicle which is substantially heavier than the majority of such vehicles. Consequently, such vehicles are generally restricted to a single site of use unless transport means such as a van with a lift platform is available. In contrast, most of the front wheel drive vehicles are separable into component parts which are light enough to be easily lifted for placement in an automobile trunk for transportation to other sites of use.